The present invention relates to an adjustment tool for an external fixator adapted for securing a first bone portion in a position relative to a second bone portion, wherein the adjustment can comprise a compression or a distraction.
An external fixator in use with a patient is usually a device comprising at least two clamping assemblies for receiving at least one bone pin each. In a preferred embodiment, each clamping assembly comprises a second clamp for receiving a rod of an external fixator which extends over the fracture. If a compression or a distraction is to be applied, at least one clamping assembly has to be loosened with the risk that the angular orientation of the corresponding bone pin engaging the bone from one side of the fracture loses its orientation.
U.S. Pat. No. 5,304,177 discloses an integrated adjustable fixator having two clamping assemblies within which each receives a bone pin to be entered into a bone of a patient of on each side of a fracture. Between the two clamping assembling holding the bone pins there is provided a main body having a worm in order to vary the distance between the two clamping assemblies. The device allows adjusting the distance between such two bone pins and therefore can be considered as a compression and/or distraction tool itself.
U.S. Pat. No. 7,261,713 discloses another bone fixator which is adjustable, wherein two multipin clamping assemblies are attached to a longitudinal main body. The main body allows different orientations of the clamping bodies and comprises a longitudinal translation element which allows shifting the positions of the two multipin clamping assemblies.
The prior art allows an easier adaptation of the distance between the clamping assemblies providing bone pins on each side of a fracture in a bone of a patient but they fail to provide a rigid frame. The existence of pivoting joints between the clamping assemblies necessitates some forces to block the universal joints.